1. Field
The embodiments discussed herein are directed to an electric circuit device that supplies power to a load circuit in the electric device.
2. Description of the Related Art
One of functions to reduce power consumption of a semiconductor integrated circuit used in an electric apparatus is power gating. The power gating stops the power supply to a specific block of the load circuit in a standby state. Thus, unnecessary power consumption of the specific block in a standby state is reduced and hours of operation of a portable electric apparatus increase.
The load circuit in the semiconductor integrated circuit includes a logic circuit including a capacitive component such as a parasitic capacitance of a transistor and a capacitive element for stabilizing a power supply voltage of the logic circuit. When connection of the load circuit with the power source is interrupted, electric charge that is charged in the capacitive component of the load circuit may be discharged by a leakage current in the load circuit. Therefore, when the load circuit is coupled to the power source again, the capacitive component in the load circuit may be charged. Since an electric rush current flows into the capacitive component, a power supply voltage decreases and the operation of the load circuit becomes unstable.
Related arts are described in Y. Kanno et al., “Hierarchical Power Distribution with 20 Power Domains in 90-nm Low-Power Multi-CPU Processor”, ISSCC Dig. Tech. Papers, pp. 540-541, February, 2006 and in P. Royannez et al., “90 nm Low Leakage SoC Design Techniques for Wireless Applications”, ISSCC Dig. Tech. Papers, pp. 138-139, February, 2005.